Electric furnace



Decn 10, 1929,L T. F. BAaLY ELECTRIC FURNACE Filed Jan. 28. 1928 gyn/manto@ T I7 Bal@ m Gnome@ Patented Dec. 10, 1929 UNITED STATES PATENT OFFICE ELECTRIC FURNACE Application illed January`28, 1928. Serial No. 250,220.

The invention relates to electric furnaces for reducing and carburizing purposes and is particularly adapted for the production of synthetic pig iron from scrap steel. and

the like and the reduction of silicon and the like.

The object of the improvement is to provide a furnace of inverted cone shape having an electrode at its lower and smaller end 1o and movable electrodes at its upper end adapted to be moved downward toward the lower electrode in paths substantially paralleling the side walls of the furnace and substantially in alignment with the upper end of the lower electrode.

An object of the cone shape is to have a higher resistance near the bottom of the furnace where the molten material collects after passing through the carbonaceous resistor 2o having a gradually decreasing cross section as it nears the bottom of the furnace so as to increase the electric resistance at this In order to assist in increasing the resistance in the lower portion of the furnace, the upper partof the side walls of the furnace may be lined with carbon whereby a portion of the current will thus be carried'through this carbon lining, while the entire current must pass through the resistor and material in the lower portion of the furnace.

A still further object of the invention is to provide a central charging opening at the top of the furnace whereby the charge may be entered between the several upper elec- -trodes, the material thus charged forming in the usual operation a closing of the opening, preventing the flare of high temperature arcs from rapidly destroying the roof as is the case where the electrode or electrodes are in the center of the furnace and the charge is placed around the electrodes either through an opening in the side wall, or if charged through the top of the furnace, around the electrodes, in which case the furnace must be operated as an open top furnace, resulting in a great loss of heat and the volatilization of material under treatment.

Another object of the improvement is to provide a removable bottom containing the bottom electrode and a tap hole so that in case of repair of either one or both of these portions, the bottom may be completely removed and repaired or a spare bottom with these parts may be placed on the furnace.

The above and other objects may be attained by constructing the furnace in the manner illustrated in the acompanying drawing, in which The figure is a vertical section through the improved furnace.

Similar numerals refer to similar parts throughout the drawing.

The upper portion l, of the furnace, may be supported as by the structure 2, and preferably comprises the steel shell 3, and refractory inner portion 4, which may be lined with carbon, as shown at 5.

An intermediate portion of the furnace, generally indicated at 6, may be constructed in substantially the same manner as the upper section, and may be supported thereon as by the flanges 7 and bolts 8.

Wheels 9 may be carried by this intermediate section of the furnace for engagement upon the rails 10, whereby this portion of the furnace may be disconnected from the upper portion and removed for repairs or replacements.

The bottom portion of the furnace may comprise'a steel shell 11 and refractory lining 12, and preferably carries the lower electrode 13 axial of the cone shape of the furnace and tap hole 14. This bottom portion may be connected to the intermediate section of the furnace as by the tie-bolts 15, and carries the wheels 16 for engagement upon the rails 17 whereby the bottom may be disconnected and removed for the purpose of repairing or replacing the lower electrode and tap hole.

The entire furnace is of inverted, cone shape, tapering downward toward the bottom section, and the upper electrodes 18 are slidably located through the roof and arranged to be extended down to any desired distance within the furnace, parallel to the side walls and slightly spaced therefrom.

As shown in broken lines, in the drawing, the upper electrodes are movable in a path parallel with the adjacent side walls of the furnace, and substantially in alignment with and their center lines converging at the center of the upper end of the lower electrode.

The charging opening 19 is centrally located in the roof of the furnace, whereby ma terial will be charged into the top of the furnace between the upper electrodes.

The interior of the furnace may be substantially filled, between the lower and upper electrodes, with a carbonaceous material such as coke, indicated. at 20.

By locating the upper and lower electrodes in the same circuit, it will be seen that current will pass through this body of coke between the electrodes, the coke producing a resistance to the current and forming a resistor element.l

The coke will thus be maintained at an er;- tremely high temperature owing to the resistance to the electric current passingl through the same and as material such as scrap steel or the like, indicated at 2l, is charged upon the top of the coke, he same will be melted down and will trickle downward through. the coke, forming a pool of molten material in the bottom of the furnace as shown at 22.

It will be seen that the carbon lining 5 will carry a portion of the current in the upper part of the furnace, while the entire current that flows to the bottom electrode 'must pass through the resistor in the lower part of the furnace, thus increasing the resistance there- 1n.

It will also be seen that the gradually decreasing cross section of the furnace toward the bottom will increase the resistance at this point.

I claim:

1. A furnace of inverted cone shape, a reside walls located in the area adjacent to the arc, the portion of the wall below the carbon lining extending entirel to the bottom and to the lower electrode and eing of non-conducting material.

2. furnace of inverted cone shape, a resistor material within the furnace, an electrode at the lower end of the furnace, a plurality of movable electrodes ,in the upper end of the furnace and substantially parallel to the side walls thereof, a carbon lining in the upper portion of the side Walls adjacent the upper portion of the resistor material and adjacent the upper electrodes, the lower portion of the side walls extending between the car bon lining and lower electrode being of nonconducting material, and means for passing an electric current from the upper electro to the resistor material, then parta y through the upper portion of the resistor material and partially through the carbon lining, and then entirely through the lower portion of the resistor material to the lower electrode, whereby a 'very high resistance is se 70 cured at the lower portion of the furnace.

In testimony that I claim the above I have hereunto subscribed my name.

THADDEUS F. BAILY. 

